Preliminary reliability and validity of the shoulder functional reach score

The purpose of this study was to determine (a) if the newly developed shoulder functional reach score (SFRS) is reliable; (b) if the SFRS demonstrates construct validity by being able to differentiate between patients' symptomatic and asymptomatic shoulders; (c) if the SFRS is able to detect changes over time; and (d) if the potential changes in the SFRS demonstrated criterion validity at three different time intervals by being associated the Numeric Pain Rating Scale (NPRS) and Shoulder Pain and Disability Index (SPADI).

Patients were consecutively screened for consultation related to complaints of shoulder pain. Thirty-eight subjects agreed to participate and signed informed consent. Twenty-nine subjects fulfilled the study after the 4 weeks of follow-up. Outcome measures were collected at the initial evaluation and at the first follow-up visit prior to the initiation of treatment. Data were then collected after 2 and 4 weeks of treatment.

There were statistically significant differences between symptomatic and asymptomatic shoulders on the SFRS. Intratester reliability of the SFRS was intraclass correlation coefficient (ICC_2,1 ) = 0.94. Intertester reliability of the SFRS was ICC_2,1  = 0.92. Statistically significant differences were observed between the initial evaluation, 2 and 4 weeks for the SFRS, SPADI, and NPRS. Moderate (r_s  = 0.62) to strong (r_s  = 0.87) positive correlations were observed between the NPRS and SPADI. Moderate negative (r_s  = -0.50-0.51) correlations were found between the SFRS and the SPADI. Moderate negative (r_s  = -0.36-0.54) statistically significant (p < 0.05) correlations were found between the SFRS and the NPRS.

In this small sample, the SFRS was an objective, reliable, and valid tool for assessing shoulder active range of motion in a clinical setting.